Sun Unleashes Massive Solar Flares in One-Two Punch

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Just as many Americans got back to work after the long Labor Day
weekend, the sun jolted to life as well, unleashing a massive
solar flare just one day after another sun storm sent a stream of
particles racing toward Earth.

The X-class solar flare — the
most powerful type of sun storm — erupted at 6:12 p.m. EDT
(2212 GMT) on Tuesday (Sept. 6) and hit its peak strength eight
minutes later, according to a space weather update by the
National Oceanic and Atmospheric Administration (NOAA). The flare
occurred less than 24 hours after another less intense but still
dramatic solar storm.

Several different satellites watched the action unfold, including
NASA's Solar Dynamics Observatory, which constantly records
high-definition videos of the sun in several different
wavelengths. [ Photo
of the X-class solar flare ]

The Tuesday event registered as an X2.1-class solar flare, while
Monday's storm topped out at a still-powerful M5, NOAA officials
said. Strong solar flares are classified according to a
three-tiered system: X-class flares are the most powerful,
M-class are of medium strength and C-class are the weakest.

September solar storms

Researchers are still taking the measure of the big Tuesday sun
storm. It may also have produced a coronal mass ejection (CME)
aimed at Earth, researchers said, but as of Tuesday evening it
was too early to tell.

CMEs are massive clouds of solar plasma that can streak through
space at up to 3 million mph (5 million kph). CMEs that hit Earth
can wreak havoc on our planet, causing disruptions in GPS
signals, radio communications and power grids. [ Sun's
Wrath: Worst Solar Storms in History ]

Monday's event, which took place at 9:50 p.m. EDT (0150 GMT on
Tuesday), did spawn a CME. It was a relatively slow one,
traveling at less than 720,000 mph (1.2 million kph), NASA
officials said. And even if this cloud of charged particles hits
Earth in a few days' time, it likely won't cause much damage.

"This CME is not expected to cause significant geomagnetic storm
activity, and further analysis is currently underway to better
refine the CME timing and magnitude," officials at NOAA's Space
Weather Prediction Center wrote in an update Tuesday.

Monday's M5 solar flare erupted from the middle of the sun's disk
as seen from Earth's perspective. The explosion caused a slight
increase in solar energetic protons about 26,000 miles (41,840
kilometers) above the Earth's surface, NASA officials said.

The angry sun

The powerful storms unleashed on Monday and Tuesday aren't
isolated incidents. Solar activity has been ramping up over the
last few months as the
sun has roused itself from an extended quiescent phase in its
11-year activity cycle.

Just last month, for example, the sun let loose with an X6.9
solar flare, which was the most powerful solar storm since
December 2006, NASA scientists said. That storm, which erupted
Aug. 9, also generated a CME, but it was not aimed at Earth.
Another powerful event, an X2.2-class flare, occurred on Feb. 15
of this year. Tuesday's X2.1 was the third most powerful flare of
2011.

Scientists expect activity in the current cycle — known as Solar
Cycle 24 — to peak around 2013.

You can follow SPACE.com senior writer Mike Wall on
Twitter:@michaeldwall.
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